Code Definition

B1021 — LH deployment loop Circuit resistance High

System: Body  |  Type: Manufacturer-Specific  |  Make: Holden

About B1021

B1021 is a manufacturer-specific body diagnostic trouble code recorded for Holden vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1021 is stored, the module has detected a signal or supply voltage higher than the expected operating range.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

B1021 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Restraint Control Module (RCM) continuously measures the resistance of each airbag deployment loop to verify the squib circuit is healthy and ready to fire within specification. B1021 sets when the RCM detects that the left hand deployment loop resistance is above the acceptable high threshold but not fully open, indicating a degraded connection somewhere in the circuit. On Holden vehicles the left hand loop typically services the driver's airbag via the clockspring, and in some configurations the left side curtain or thorax airbag. With this code active the SRS warning light illuminates, ...

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